1. Field of the Invention
The present invention relates generally to seat back and seat frame constructions forming portions of seat integrated restraint assemblies. More particularly, the present invention discloses a cup-style spacer for attaching an upper arm of a seat back to a seat frame, as well the shear staking the attachment nut with the cup spacer in order to maintain a xe2x80x9chard clampedxe2x80x9d condition and to prevent loosening of the spacer.
2. Description of the Prior Art
Seat integrated restraint assemblies are known in the art for vehicle applications and typically a seat back secured through the use of fasteners to a seat bottom. Due to the various types of inertial loads and forces applied to seat integrated restraint assemblies, the integrity of the attachment of the upper arm to the seat frame is critical. It has further been found that the use of a simple nut in engagement with a bolt will not withstand the vibration testing parameters established for ensuring that the bolt and nut will not loosen or separate in use.
One attempt at resolving the problem of loosening of the bolt and nut has been the provision of a spacer/nut assembly in which the contact surface of the spacer mates with the seat frame rather than the nut surface. In this manner, the seat frame is locked to the spacer and the bolt is always under tension regardless of vibration or lateral movement of the seat frame. However, it has been found that the use of such spacer/nut assemblies suffer from the shortcomings of the relative mass associated with the machined and solid steel spacer, as well as limitations as to its use with typical nuts which also require specific machining processes, making the spacers and nuts fairly expensive to produce.
Additionally, the machining process known as xe2x80x9cshear stakingxe2x80x9d or xe2x80x9cupset stakingxe2x80x9d (that being the forcible scraping or compressing of portions of material from an object) is also known in the art. In particular, it is known in the art to upset stake a two-piece nut and collar spacer assembly, such as described in the prior art above, and for the purpose of securing a seatback arm to a seat bottom frame.
An additional prior art example of a staked stud and shell arrangement is illustrated in U.S. Pat. No. 4,820,076, issued to Rossigno, and which teaches the shell as including openings with a reinforcing ring that is offset from a planar surface. The stud has a head with a groove located between the shank and an arcuate section adjacent its periphery. The ring is located in the groove and a cylindrical section adjacent the head is sheared to define a flange that engages the ring, causing a portion thereof to flow around the ribs, in the groove and seal a pair openings.
The present invention discloses a fastener assembly including a novel cup-style spacer for attaching an upper arm of a seat back to a seat bottom forming a part of a recliner mechanism, as well the shear staking the interiorly hollowed attachment nut with the cup spacer in order to maintain a xe2x80x9chard clampedxe2x80x9d condition and to prevent loosening of the spacer. In particular, the cup-style spacer provides a unique and two piece assembly for use in securing the seat back to the seat bottom and is a specific improvement over prior art solid steel spacers in that it provides the ability to flex about its radius adjacent to the upper seat back arm. This allows the cup spacer to compensate for irregularities, such as out of flat condition, in the mating surface of the seat frame.
In the preferred embodiment, the seat back includes first and second extending sides, each side having at least one aperture defined therethrough. The corresponding seat bottom includes first and second pivotally engaged and extending arms, each of the arms having a first side and a second side with at least one recess defined therethrough.
The fastener assembly further includes a plurality of substantially cup shaped spacers, each of the spacers having an inner annular rim defining an open interior. A plurality of multi-sided nuts are provided (typically hex headed nuts). Each of the nuts has an enlarged and substantially annular shaped end portion integrally formed therewith. An exterior configuration of each of the nuts matches the configuration of the recesses in the arms pivotally associated with the seat frame and to permit insertion of the nuts through the recesses, the enlarged annular portions abutting against the first side of each of the arms, the nuts extending beyond the second side of each arm and through the inner annular rims defined in each of the spacers.
Edge portions of each of the nuts, which are associated with boundaries established between each pair of adjoining sides, are shear staked staking against the cup spacer and to secure each of the assembled and shear staked nut and spacers to each of the first and second arms. Upon aligning the apertures located in the first and second sides of the seat back with the assembled nut and cup spacers staked to the extending arms, threaded bolt fasteners engage the seat back to the seat bottom by virtue of rotatably engaging against the inner threads defined through each of the nuts.
Additional features include the provision of a punch for shear staking the nut to the cup spacer. The punch includes an actuating portion, an end face of the actuating portion being defined by an outer annular projection in turn defining a centrally disposed and inwardly recessed interior. An inwardly facing and annular surface defining the projection being dimensioned to shear specified volumes of material associated with each of the edge portions of said multi-sided nut and in collapsing fashion against the inward bowl shape of the cup spacer in proximity to its inner annular rim.